This invention relates generally to rebreathing systems, and, more particularly, to a constant volume rebreathing system which provides a completely closed breathing system between man and the external environment. Such a system is especially useful for the collection of expired air samples from humans.
It is essential in the field of medicine as well as the space program to provide a rebreathing system which is capable of collecting non-contaminated expired air samples. Such samples, with subsequent analysis, can provide information in the following areas of interest:
1. Forensic medicine;
2. Respiratory compounds as indicators of metabolic disease and the disease state;
3. Determination of toxin in toxic exposure;
4. Determination of the degree of stress;
5. Normal compounds associated with man as related to diet;
6. Drugs and drug metabolism; and
7. The inhalation study of particles and gaseous compounds.
Heretofore, the techniques and designs which made breath by breath analysis of a subject possible was in the form of a water spirometer. In such a system no controls are included to improve data results, while in many instances leakage from ambient air causes data to misrepresent components in the subject's expired air. Furthermore, the water spirometer of the past has the following distinct disadvantages:
1. It has a water interface which may absorb the components of interest;
2. The breath by breath energy expended by the subject to operate the spirometer causes early fatigue in the subject before sufficient data can be taken;
3. The dynamic range of the water spirometer requires the subject to remain in a fixed position; and
4. The spirometer cannot be used as a respiratory simulator.
It is therefore clearly evident that a great many problems exist in the area of breath analysis. There is a complete lack of functional equipment in a field which is rapidly expanding.